In simple terms, a tooth abscess develops as a result of tooth decay. This typically occurs as a result of dental caries which causes destruction and deterioration of enamel, which is the hard protective outer layer of your tooth. This leaves the softer lower layer of tissue exposed. This layer is called dentine. With progressive deterioration of the tooth, dental caries will eventually get through this layer as well, to affect the center of the tooth (the pulp), causing Pulpitis. When the pulp in the tooth dies, the chamber becomes infected and bacteria from here will even reach the bone. When such an infection develops within the tooth it can cause severe tooth pain. The pain that radiates from the region is caused by the buildup of pus in the tooth and because of local inflammation and swelling. The pain may resolve if the pulp dies. But very often an abscess then develops and the infection will continue to cause painful symptoms and may even spread to infect the surrounding tissue.